After Bandai updated TamaTown for the Tama-Go, some people have been having a hard time finding the TamaTown sites for previous version Tamagotchis. Hopefully this illustrated guide will help.
When you go to www.tamatown.com, you'll be redirected to a page similar to that pictured below.
Scroll down that page a bit. Click the "Open" tab near the middle-bottom of the page.
A panel will slide down. It has links to the TamaTown sites for previous version Tamagotchis.